Administration sets for intravenously administering a liquid, generally called a transfusion liquid, and sometimes containing a dextrose solution, a solution of salt or water (hereinafter called a medical liquid) is widely used. In such a set a particular drug is frequently mixed with the medical liquid to be administered.
The administration set generally comprises a container containing a large volume of medical liquid, a cylindrical instillator, a flow rate control means, a fluid filter, means for removing air, an injection site for injecting additional drug mixture, fluid conduits for intermediate connection, and means for coupling inlet and outlet portions. Conventionally, when the administration set is used to supply a patient with a medical liquid mixed with a particular agent, if the agent is not liquid, it is first liquefied by using a diluent or other agents and then infused into the injection site so that the agent is mixed with the medical liquid.
This method, however, carries a risk of various kinds of contamination that are attributable to the requirements for the work of infusing a drug into the medical solution and preparatory operations therefor. Various countermeasures have been taken to avoid these risks, and to relive the medical workers from the work.
Representatives of such countermeasures are described in Japanese Patent Publication Nos. 5-60758 and 5-81271. The system taught by these publications comprises disposing a vial-like drug container in the middle of a fluid conduit for a medical liquid, and passing the medical liquid through the drug container to deliver a mixed solution containing the medical solution and drug. This type of system is referred to as a passive drug delivery system.
In that system a socket or a receptacle and a cartridge to be coupled therewith are provided. The drug container is attached to the cartridge so that, the inside space of the drug container is made to communicate with the flow path of the medical solution.
When this passive drug delivery system is used, once the drug container is docked into the cartridge, there is no chance for the drug in the container to be exposed to the air, and all the mixing operation is automatically carried out by the medical solution, so that very high safety can be secured, and so that the work of the operator can be saved.
However, although the delivery of the drug is carried out under strictly controlled conditions, there are cases in which the removal or renewal of the drug container is needed after the drug has been delivered. These requirements are not appropriately met by the well-known system mentioned above. In other words, once the passive drug delivery system has been established, the drug container cannot easily be removed. This is because the system is generally designed for the medical solution to pass through the container to form a portion of the flow path for the medical solution.
What would therefore be advantageous is to provide a receptacle for a passive drug delivery system which can be used without interruption even when a drug container is to be removed or replaced, or which can be used without a drug container when it is not needed.